Later, the prince of Troy, Paris, assisted by Aphrodite, abducted Helen, Menelaus’ wife, and went back to Troy. Agamemnon agreed to help his brother to take her back and declared war on Troy. However, as the ships were ready to set sail, Agamemnon’s army infuriated the goddess Artemis, who sent a number of misfortunes against them. The prophet Calchas realised that Artemis’ fury would only be appeased by the sacrifice of Agamemnon’s daughter Iphigenia. This part of the myth has different versions, as to whether Iphigenia accepted her fate or she was tricked thinking she would be married to Achilles. In the end, she was sacrificed; however, there are alternatives to this part as well. Some sources say that she was sacrificed, while in others, Artemis replaced her with a deer and took her to the region of Tauris in the Crimean Peninsula. Agamemnon never found out.

After the end of the war, Agamemnon returned home, where Clytemnestra had started an affair with Aegisthus. The two of them plotted against Agamemnon and killed him, thus Aegisthus becoming the ruler of Mycenae again. Orestes, Agamemnon’s son, later avenged his father’s death by killing the two lovers; however, this caused the wrath of the Erinyes, because he committed matricide.